# CVE-2026-123608: Hickory DNS hickory-proto denial of service in BinEncoder

Source: https://junglewise.ai/threats/cve-2026-123608-hickory-dns-hickory-proto-from-0-3-1-before-0-26-1-contains-a  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-08. Updated: 2026-11-08  
License: CC BY 4.0 with a link back

CVE-2026-123608 · Severity: high · CVSS 7.5 · Published 2026-11-08

Hickory DNS is a DNS client library used in Rust applications. A flaw in its message encoding function allows attackers to send specially crafted DNS messages that consume excessive CPU, causing denial of service by exhausting server resources. This can impact any service relying on hickory-proto to process DNS messages.

Technologies: [Hickory-Dns Hickory-Proto](https://junglewise.ai/threats/technologies/hickory-dns-hickory-proto). Vendors: [Hickory-Dns](https://junglewise.ai/threats/vendors/hickory-dns).

## Quick answers

**Is CVE-2026-123608 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-123608 being exploited in the wild.

**How severe is CVE-2026-123608?** High severity, with a CVSS score of 7.5, published 8 November 2026.

**Which products and versions are affected?** Hickory-Dns Hickory-Proto 0.3.1 through 0.26.0.

**Is there a fix for CVE-2026-123608?** Yes: fixed in 0.26.1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-123608 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-123608?** Check whether you run Hickory-Dns Hickory-Proto at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 0.26.1

## Technical details

The BinEncoder component in hickory-proto uses an O(n²) algorithm for DNS name compression, storing candidate labels in a vector and performing linear scans to find matches. An attacker can craft a malicious DNS message with many records to introduce numerous candidate labels and trigger the linear scan repeatedly, amplifying CPU exhaustion. The vulnerability exists in versions 0.3.1 through 0.26.0 and requires network access to send the malicious message.

## Affected products

- Hickory DNS hickory-proto 0.3.1 through 0.26.0

## Timeline

- 2026-05-01: disclosed
- 2026-11-08: advisory

## References

- [https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-q2qq-hmj6-3wpp](https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-q2qq-hmj6-3wpp)
- [https://www.vulncheck.com/advisories/hickory-dns-hickory-proto-0.3.1-before-0.26.1-cpu-exhaustion-via-binencoder-name-compression](https://www.vulncheck.com/advisories/hickory-dns-hickory-proto-0.3.1-before-0.26.1-cpu-exhaustion-via-binencoder-name-compression)

## Related threats

- [Hickory DNS NSEC3 closest-encloser proof unbounded loop](https://junglewise.ai/threats/cve-2026-123607-hickory-dns-hickory-proto-0-25-0-alpha-3-through-0-25-2-and)
- [Hickory DNS DNSSEC validation bypass via RRSIG Signer's Name](https://junglewise.ai/threats/cve-2026-123605-hickory-dns-hickory-proto-0-1-through-0-25-0-alpha-3-and-hickory)
- [Hickory DNS IPv4-mapped IPv6 canonicalization bypass](https://junglewise.ai/threats/cve-2026-123603-hickory-proto-and-hickory-resolver-0-26-0-before-0-26-2-hickory)
- [Hickory DNS NSEC3 comparison operator inversion](https://junglewise.ai/threats/cve-2026-123601-hickory-dns-hickory-proto-0-25-0-through-0-26-0-alpha-1-and)
- [Hickory DNS DNSSEC validation bypass in NSEC3 NODATA](https://junglewise.ai/threats/cve-2026-123600-hickory-dns-hickory-proto-0-25-0-alpha-3-through-0-25-2-and)